Method of and means for forming housing wall sections



March 29, 1966 w. A. MARTIN METHOD OF AND MEANS FOR FORMING HOUSING WALL SECTIONS Filed May 24, 1962 3 Sheets-Sheet 1 urn ATTORNEYS March 29, 1966 w. A. MARTIN METHOD OF AND MEANS FOR FORMING HOUSING WALL SECTIONS Filed May 24, 1962 3 Sheets-Sheet 2 2 mm A? t INVENTOR. WAYNE A MARTIN ATTORNEYS a moi March 29, 1966 w. A. MARTIN 3,242,713

METHOD OF AND MEANS FOR FORMING HOUSING WALL SECTIONS Filed May 24. 1962 3 Sheets-Sheet 3 v Ho ,|O Hb r n FIG.6 )Ha F'IG.8

10" l L INVENTOR. WAYNE A. MARTIN 12 BY FIG.9

United States Patent 3,242,713 METHOD OF AND MEANS FOR FORMING HOUSING WALL SECTIONS Wayne A. Martin, Berkley, Mich., assignor to Lyon Incorporated, Detroit, Mich, a corporation of Delaware Filed May 24, 1962, Ser. No. 197,374 13 Claims. (Cl. 72359) The present invention relates to a new and improved method of and means for forming housing wall sections of the kind which are adapted to be assembled together to provide large size lightweight housings of great strength such as for ballistic and like devices of which rocket engine chambers are exemplary, containers, submersible chambers, etc., wherein a thin wall membrane is required with ample reinforcement against collapse due to pressures imposed against the wall.

Due to the large sizes required in the individual sections it becomes impractical to mold or cast such sections in metal and, further, casting does not provide adequate unit strength in a thin section. Rolling such sections affords difficulties due to limitations upon practical sizes of metal rolling equipment and problems of metal flow and displacement. Furthermore, power expenditures and available pressures are limitations. There is also the problem of effective formation of curved sections.

It is an important object of the present invention to provide a new and improved method of and means for efiiciently, economically, and rapidly forming reinforced thin wall sections for use in multi-section lightweight housings.

Another object of the invention is to manufacture according to a novel method thin wall plate sections having on one face thereof a pattern of integral reinforcing ribs.

A further object of the invention is to provide new and improved apparatus for shaping thin plate sections with a pattern of integral reinforcing ribs.

Still another object of the invention is to provide a new and improved method of and means for affording metal plate sections with a uniform pattern of thin skin or membrane areas and integrated reinforcing ribs.

Yet another object of the invention is to provide a new and improved method of and means for providing a thin metal section with a pattern of crossing integral reinforcing ribs.

It is also an object of the invention to provide a new and improved method of and means for shaping, hardening and sizing integral reinforcing ribs on metal plates by cold Working;

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a fragmentary top plan view of novel apparatus for shaping thin wall metal sections with ribs according to the present invention;

FIGURE 2 is a sectional detail view taken substantially on the line IIII of FIGURE 1;

FIGURE 3 is a sectional detail view taken substantially on the line III-III of FIGURE 1;

FIGURE 4 is an enlarged fragmentary sectional detail view of the area IV of FIGURE 2;

FIGURE 5 is a schematic illustration of the relationship of the divider and sizing strips of the apparatus;

FIGURE 6 is a more or less schematic elevational view of a housing utilizing metal sections of the type adapted to be made by the present method and with the present apparatus;

FIGURE 7 is a plan view of a metal section made according to the present method and in the present apparatus and of a type adapted to be utilized in the housing or casing illustrated in FIGURE 6;

FIGURE 8 is an end elevational view of the plate section shown in FIGURE 7 and looking toward the left; and

FIGURE 9 is a sectional view taken substantially on the line D(IX of FIGURE 7.

Reference will be made first to FIGURES 6-9 which illustrate an embodiment of housing structure and metal sections exemplary of the utility of the present invention. As the description progresses, it will be readily apparent that numerous other uses for metal plate housing sections made according to the present invention will be readily found.

A casing or housing 10' as shown more or less schematically in FIGURE 6 comprises a built up unit of complementary thin, integral rib reinforced metal sections of the kind more specifically illustrated in FIG- URES 7-9 and generally identified as 11. Since the exemplary housing 10 is of generally oval shape in longitudinal section and of cylindrical cross-section throughout the major extent of its length, with semi-spherical opposite ends, the thin metal plate sections are provided in standard shapes to cooperate with one another in edgeto-edge relation in building up the casing. In this instance, adjoining rows 11a of the casing wall sections are longitudinally straight but circumferenti'ally complementally curved shape, as are also remaining adjoining rows 11b of the casing wall sections, al-l cooperating to produce the cylindrical portion of the housing. In each of the semi-cylindrical end closure portions respective rows of complementary longitudinally and transversely appropriately curved casing sections are joined in a row which adjoins the respective endmost cylindrical rows 11a and 11b, while a second row of end closure sections 11d also appropriately longitudinally and transversely curved intervenes between the row of sections 110 and a circular end tip member He at one end and 11] at the opposite end.

While it should be understood that every casing section of the entire housing 10 desirably embodies the same general structure as to wall thickness and reinforcement, inclusive of all of the rows of sections as Well as the end cap terminal members lie and 11 one of the casing sections 11 of the rows 11d has been selected as exemplary for a more detailed description as to structure and in respect to the method of the present invention of making the same. Thus, the section 11 comprises a wall or membrane 12 of as thin cross-section as pract-ible for the use to which the housing of which it will be a component demands, including such factors as over-all size, tensile and compression stresses, bending stresses, and the like. Where, for example, the housing 10 is to provide a rocket engine casing on the order of 39 to 40 ft. long by about 30 ft. in diameter, the exemplary casing section 11 may be of a length of about 8 to 10 ft. and since it is of a generally wedge or gore shape about 7 to 8 ft. across at its maximum width and about 3 ft. across at its narrowest width. On its inside or concave face, the exemplary section 11 has a pattern of crossing integral narrow reinforcing ribs comprising longitudinal ribs 13 and transverse ribs 14 all integrated for mutual reinforcement and joining a continuous marginal rib 15 which is uniformly spaced inwardly, that is inset, from the edges defining the plate section as shown thus leaving a narrow margin 17 entirely about the perimeter of the section 11. By having the crossing reinforcing ribs 13 and 14 in a uniform pattern such as the waffle pattern shown, a quite uniform reinforcement per unit area is attained. In the large exemplary size mentioned, the rib spacings are such as to provide a pattern of quadrangular areas which for the most part are on the order of 8 inch included squares while the ribs may be on the order of about /8 inch crest width and on the order of 1 inch or slightly higher rib height. At suitably spaced intervals the rib 15 is shown as provided with holes 18 which are useful in effecting assembly of the sections 11 with companion sections in the housing 10.

For lightweight, a lightweight alloy such as aluminum may be used in producing the sections 11 although where use requirements are for some other material such as steel, alloy steel, stainless steel, beryllium, titanium, and the like such materials may be used.

According to the method of the present invention, each of the housing sections 11 is initially shaped to porvide substantially the ultimate outline and outer face or convex contour and of a thickness which will provide sulficient material to enable displacement of enough material from the between-rib areas of the blank during a reduction in thickness of such areas to afiord ample material to raise the pattern of ribs on the inner, concave face of the blank. Then, while maintaining the outline perimeter of the blank and the outer face curvature positively, the between-rib areas are subjected to coining pressure and the material of such areas displaced substantially uniformly and to a controlled depth from the areas into the ribs surrounding the areas. In so doing, the material displaced from the between-rib areas in caused to displace andfiow into the desired rib formations raised from the coined surface. In effecting the coining thinning of the between-rib areas and displacement of material into and raising of the ribs, the between-rib areas as well as the ribs are work hardened and are also sized.

Where a highly malleable material is used in fabrication of the sections 11, complete shaping of the thinned wall areas and raising as well as shaping of the rib grid can be accomplished by cold working without intermediate annealing steps, although it may be desirable to give the finished piece a final anneal to relieve uneven stresses. However, in certain materials the work hardening resulting from the present method is of such uniformity as to avoid the need for annealing. One of the features of the method which enables the attainment of this result resides in a progressive formation of the waffle-like pattern of thin areas and rib grid.

A further and more comprehensive understanding of the method of the present invention will be had as the description proceeds in connection with FIGURES 1-5 disclosing special coining die apparatus for practicing the method. This apparatus includes a lower die assembly 19 and an upper die assembly 20. The lower die assembly 19 is adapted to be supported in stationary relation on a press bed 21, while the upper die assembly 20 is arranged to be carried by a ram head member 22 which is arranged to be driven in pressure and return strokes by suitable die press apparatus of any suitable or well known character.

In the illustrated arrangement, the lower die assembly 19 includes a base plate 23 supporting within a shallow interlock recess 24 in its upper face a frame member 25 in slidable guiding engagement with the perimeter of a vertically reciprocable die plate 27 which normally seats in firm supported relation upon the bed plate 23. Ejector pins 28 operating through suitable bores in the press anvil or bed 21 and the bed plate 23 are adapted to be actuated in any suitable manner from below to move the die plate 27 upwardly from the bed plate 23 and relative to the frame member 25 which is rigidly secured to the bed plate 23 as by means of screws 29. While the frame member 25 may be made from a single piece of material, it may also be comprised of a plurality of complementary sections or lengths of material.

Since a principal function of the lower die assembly 19 is to support a blank for one of the housing sections 11, both the frame 25 and the die plate 27 are shaped complementary to such a blank. For this purpose, the frame 25 is of an inside outline complementary to the perimeter of such a blank, and the die plate 27 is provided with an upper face 30 which is shaped complementary to the outer curved face of the blank. Further, as best seen in FIGURES 2-4, the inner surface of the frame 25 projects uniformly above the edges of the surface 30 whereby to afford a retaining, edge confining perimeter for the edge of the blank.

It will be understood, of course, that for a casing construction 10 of the type depicted in FIGURE 6, there will have to be a separate die assembly for each of the series of housing wall sections particularly conformed for that series. Thus, there will have to be a separate die configuration for each of the row series of sections 11a through 11d, and where the end disks 11a and 11 are difierent there will have to be a separate die for each of such end disks. However, the general construction and operation of the die assembly will be substantially the same in each instance since each of the several section shapes embodies the same final structure, that is, a thin membrane-like wall with a reinforcing grid of integrated ribs.

Before placing a blank for one of the wall sections 11 in the die, the blank is preformed to its ultimate outer face shape, whatever that may be, such as compound curvature, single plane curvature, convex, or even flat if required. Further, each of the blanks will be of an initial plate or membrane thickness calculated to afford ample displaceable material for formation of the grid of reinforcing ribs as the major areas of the disk are thinned down to the desired wall thickness of the completed wall section. In a preferred form, the preformed blank has the marginal rib 15 at least partially raised, that is preformed, as best seen in FIGURE 4. Also, the marginal portion 17 surrounding the rib 15 may be of preformed thickness as shown, thus aifording a thorough marginal reinforcement for the preformed blank enabling its successful handling Without undue danger of warpage or marginal deformation or damage.

Initially, the performed blank is placed within the forming cavity provided by the die surface 30 and the upper inner wall portions of'the frame 25. Thereby the die surface 30 provides a solid backing for the outer face of the blank, While the frame 25 positively confines the blank against displacement in any lateral direction, that is in any direction in the plane of the blank. During such loading of the lower die assembly 19, of course, the upper die assembly 26 remains in a backed off, raised clearance relation to the lower die assembly. If desired, of course, the lower die plate 27 may the raised above the upper side of the frame 25 by means of the ejector pins 28 in order to facilitate loading of the blank onto the sunface 30, whereafter the die plate 27 is lowered into the bottomed operative position as shown in FIGURE 2.

As the upper forming die assembly 20 is driven by the press ram in a coining stroke toward the lower forming rdie assembly 19, any selected one or more of a set of coining punches 31 is adapted to be ooiningly pressed against the opposing inner face of the housing section blank to effect displacement of material in the limited area of the blank engaged by the coining face of the punch toward and into a raised rib formation about the respective punch. For this purpose, the upper die assembly 20 includes a head plate or die shoe member 32 carried by the downwardly facing surface of the ram or bolster member 22. In this instance, the die shoe member 32 comprises a flat plate of suitable thickness which carries on its lower face means for supporting the set of coining punches 31. Herein such means comprise a set of vertical divider and sizing strip bars 33 and 34 arranged in a pattern corresponding exactly to the grid pattern of the reinforcing ribs 13 and 14, respectively. That is, the grid bars '33 correspond exactly to the ribs '13 and the strip bars 34 correspond exactly to the ribs 14. As best seen in FIG. 1, the strip bars 33- and 34 are disposed in crossing relation to provide vertical guideways or sockets corresponding in cross-sectional size in a horizontal plane to the outline dimensions of the re spective wall membrane areas enclosed by the reinforcing rib waffle grid. On their upper edges, the strip bars 33 and 34 are straight, while the lower edges of the bars are properly conformed to the crest planes of the respective reinforcing ribs 33 and 34 to which the bars correspond.

Conveniently, the strip bars 33 and 34 are crossingly related to one another on the order of the conventional cell dividers used in egg crates and bon bon boxes. For this, the strip bars 33 have downwardly opening slots 35 receptive of portions below upwardly opening slots 37 in the strip bars 34, as shown in FIG. 5, in such a manner as to maintain the upper edges of the two crossing sets of bars in parallel planes while the lower edges are properly correlated for crest sizing of the reinforcing ribs 13 and 14.

In this instance, the strip bars 34- project upwardly to a predetermined extent above the upper edges of the crossingly interconnected strip bars 33, and the upper margins of the strip bars 34 are retainingly engaged and bottomed within respective slots 38 opening downwardly for this purpose in the lower face of the plate member 32. At suitable intervals the upper margins of the strip bars 34 are formed with attachment head flanges 39 received in suitable recesses 40 in the lower face of the plate member 32 and enabling attachment of the strip bars 34 to the plate member 32 as by means of screws 41 (FIGS. 1 and 2).

At least partial support for the strip bars 33, in addition to that afforded by the crossing connections with the strip bars 34, is afforded by respective combination punch guiding, shaping and stop bar flanged members 42 and 43 secured as by screws 44 to the lower face of the plate member 32 at the opposite ends of the perimeter defined by the coining punch assembly. As best seen in FIG. 2, and also on reference to FIG. 1, the bar members 42 and 43 provide socket guide surfaces in cooperation with the adjacent strip bars 34 for the coining punches 31 along the respective ends of the coining punch assembly perimeter. Suitable notches in the bar members 42 and 43 receive end projection lugs 45 on the contiguous ends of the strip bars 33.

Means are provided for selectively controlling the sequence in which each individual one of the coining punches 31 will become operative to coin its designated area of the housing section blank. To this end, the upper edges of the strip bars 33 are, in the assembly, sufficiently spaced below the lower face of the plate member 32 to provide clearance for reception over such upper edges of respective laterally projecting overhanging retainer flanges 47 (FIG. 3) on the upper end or head portions of the respective coining punches 31. In addition, this clearance is ample to accommodate respective gag bars 48 which slidably overlie the heads of the punches 3'1 and bottom against the lower face of the plate member 32. As evident in FIGURES 1 and 2, the gag bars 48 are longi tu dinally slidably guided between the upper portions of the strip bars 34 except at the opposite ends of the shaping perimeter of the upper die assembly 20, where the bar members 42 and 43 provide guiding surfaces.

At each side of the shaping perimeter of the upper die assembly 20, a respective combination stop, shaping and guide flanged bar 49 is secured to the plate member 32 similarly as the end bars 4-2 and 43. These side bars 49 cooperate with the adjacent strip bars 33 to provide a socket wall for guiding the associated punches 31. In addition, the bars 49 have respective rabbet groove shoulders 50 receptive of the adjacent overhanging retaining flanges 47 of the associated punches. Further, the bars 49 provide on their upper slide surfaces 51 for the overlying gag bars 48.

Each of the gag bars 48 has a first or non-gagging portion 48a which is thinner than a second or gagging portion 48b by the amount of displacement in thickness of material in the wall portion of the wall section blank to be effected by each of the punches 31. Initially, the nongagging portions 48a of the gag bars are arranged to overlie the heads of the punches 31. In this relationship the punches are adapted to float freely vertically slidably within the sockets afforded by the crossing strip bars 33 and 34 within at least a range, as indicated in FIG. 3, wherein when the combination stop bars 42, 43 and 49 engage the frame 25 to bring the upper die assembly 20 to a gauging stop, the punches under the non-gagging portions 48a will have no coining eflect on the underlying work blank. However, any punch or punches over which the gagging portion 48b of any one of the gag bars 48 has been shifted by a longitudinal sliding movement of the gag bar will be held by such gagging portion in coining position and as the upper, coining die assem bly 20 drives toward the stop position will coin the area opposing the coining end or nose of the punch. FIG- URES 2 and 3 show certain of the punches gagged for coining while the remaining punches are ungagged and \thus free to move to non-coining position in the coining stroke of the press.

Desirably, the frame 25 is provided with a rabbet groove stop shoulder formation 52 against which the stop bars 42, 43 and 49 engage at the termination of each coining stroke of the press. This gauges the coining depth of the punches 31 in conjunction with the gag bars 48.

As shown in FIGURES 2, 3 and 4, each of the stop bars 42, 43 and 49 in the stop position overhangs the adjacent marginal rib 15 and marginal portion 17 and has a holddown and size-maintaining downwardly projecting rib 53 which engages or at least overlies the marginal portion 17 of the wall section blank so closely as to maintain its size in each stroke of the press. Inwardly alongside the rib 53 is provided a rib shaping and sizing groove 54 shaped to receive the fully formed rib 15 therein. Projecting downwardly from the respective stop bar within the grooves 54 at suitable intervals are hole shaping pins 55 for shaping the indexing holes 18 in the rib 15 during shaping of the rib. In FIGURE 4 the rib 15 is shown in its preformed partially raised condition while in FIGURE 3 the rib 15 is shown after it has been completely raised by displacement of material thereinto from the contiguous area of the work blank coined by the adjacent punch 31.

In operation, a preformed housing section blank 11 is loaded into the lower die assembly 19. One or more of the gag bars 48 is adjusted to gag the first one or two punches 31 at the side of the upper die assembly 20 from which the gag bars 48 are adapted to be progressively advanced, from the lower side of FIGURE 1, or the left side of FIGURE 3, suitable gauging means, such as gauge marks 57 being provided on the gauge bars to determine proper orientation of the gagging portion 48b with respect to each punch in the series across the die. The initial setting of the gauge bars 48 may, for example, be for the first or first and second punches in each series, or may be for only certain of the punches of certain of the series, all depending upon such factors as shape of the piece, tonnage capacity of the press, configuration of design, character of the material being formed, and the like.

The press is then operated to drive the coining die assembly 2i) in a coining strike during which the gagged punches 31 function to coin the underlying areas of the work blank and displace material therefrom into the rib forming grooves which are defined between the adjacent lower end sides of the punches 3 1 and under the respective edges of the strip bars 33 and 34 which for this purpose are located at the proper elevation to shape the crests of the respective reinforcing ribs 13 and 14. As will be observed in FIGURE 3, the punches 31 which are not gagged are nevertheless maintained by the non-gagging portions 48a of the gag bars in rib Shaping orientation with respect to the gagged punches which displace material in the coining stroke of the press.

In each succeding coining stroke of the press, one or more additional of the coining punches 31 in one or more of the series punches controlled by the respective gag bars 48 is gagged and thereby locked in coining position. Thereby, each of the reinforcing ribs 13 and 14 although only partially formed in any coining stroke is completed by displacement of additional material thereinto from a succeeding coined area in a following stroke of the press.

After all areas to be coined have been acted upon by the coining punches 31, an additional stroke or several additional strokes of the press with all of the punches gagged may be effected for final sizing.

In order to assist in advancing the gag bars 48, a cam surface 58 is afforded between the non-gagging section 48:: and the gagging section 48b of each bar. This facilitates shifting the succeeding punches 31 into gagged, coining position.

During each coining stroke of the press, the gagged punches 31 are quite solidly backed against the bolster 22 of the press ram through the solidly backed die shoe plate 32 and the gag portion 48b of the gag bar which overlies the respective punches.

After the section 11 has been fully coined, it is removed from the press, as by raising the press plate 27 by means of the ejector pins 28. Because of the successive, incremental coining and back-off strokes of the upper die assembly 20 there is little likelihood of the work piece sticking thereto and being raised from the working cavity of the lower die assembly 19 as the coining progresses. Further, there is such an extension edge area opposing the stationary confining surface of the frame 25 as to assure reasonably tight frictional retention of the edge against upward displacement of the work piece with the retreating upper die assembly 20 during back-off in a stroking cycle. However, since the confining surface of the frame 25 is only a short distance below the stop shoulders 52, upward displacement of the completed work piece is easily effected by upward shifting of the die member 27. As a result of the working to which the material displaced by the coining is subjected, effective hardening of the piece and especially the reinforcing ribs 13 and 14 is accomplished.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a method of shaping a housing casing section to be joined with other sections in fabrication of a housing, preforming a polygonal metal plate of predetermined thickness to a predetermined plane and with a partially raised reinforcing rib entirely thereabout on the margin of one face, progressively coining limited adjacent areas of said one face and thereby displacing material from said areas until a substantially thinner cross-section is attained than said predetermined thickness, in such displacement shaping the displaced material into raised reinforcing ribs bounding and separating said areas, continuing said coining until the entire area inside said preformed rib has been coined, and in the course of said coining displacing material from the coined area contiguous said preformed rib into said preformed rib to increase the height of said preformed rib.

2. In a method of shaping a housing casing section to be joined with other sections in fabrication of a housing, preforming a metal plate of predetermined thickness to a predetermined plane and with a partially raised rib entirely thereabout on the margin of one face, progressively coining limited adjacent areas of said one face and whereby displacing material from said areas until a substantially thinner cross-section is attained than said predetermined thickness, in such displacement shaping the displaced material into raised reinforcing ribs bounding and separating said areas, continuing said coining until the entire area inside said preformed rib has been coined, in the course of said coining displacing material from the coined areas contiguous said preformed rib into said preformed rib to increase the height of said preformed rib, and in raising the height of said preformed ri-b forming a series of indexing holes in the raised portion of the preformed rib.

3. In apparatus for shaping a housing blank to provide a thin membrane wall with integral reinforcing ribs, a member for supporting one face of a metal blank of greater thickness than the desired membrane thickness, and means comprising a plurality of independently and successively operable coining punches cooperable with the opposite face of the blank to effect coining pressure toward said supporting member and thereby coin predetermined limited areas of said one face of the blank into a pattern of substantially thinner areas than said predetermined thickness, said punches being separated to a predetermined extent and affording rib receiving spaces therebetween into which material displaced by the punches projects to form raised ribs on said other face of the blank.

4. In apparatus for shaping metal plate housing sections, at supporting die assembly having a member for supporting and firmly backing a metal section blank of predetermined thickness, a coining die assembly comprising a supporting member carrying a grid arrangement of vertical strip bars defining vertical punch sockets, coining punches supported in said sockets and divided by said strip bars, gag members cooperale between said supporting member and said punches to lock said punches selectively in coining positions while leaving other of the punches in non-coining relation, and means for driving the supporting member and said gag punches into coining re- 'lation to the blank supported by the supporting member. 5. An apparatus for coining a wafiie grid membrane and reinforcing rib pattern in one face of a housing casing section, a lower die assembly including a section blank supporting member and a frame around said supporting member and providing therewith a section blank receiving cavity, a reciprocable upper die assembly including means for reciprocably operating the same in a driving and return stroke relative to said lower die assembly, said upper die assembly including a die shoe member having a lower face, said lower face carrying stop bars projecting downwardly and engageable in stopping relation against :said frame, said stop bars having therebetween crossing strip bars defining vertical sockets, coining punches slidably vertically reciprocable in said sockets and having means cooperating with said stop bars and said strip bars to retain the punches against dropping from said sockets, said punches having lower coining ends adapted to project below said strip bars and below said stop bars, the lower edges of said strip bars between said punches defining rib forming grooves between the punches, and gag bars longitudinally movable between said die shoe member and said punches and having non-gagging portions and gagging portions selectively movable into position over said punches to enable selective locking of selected ones of the punches for coining engagement with the blank section supported by said supporting member within said cavity upon movement of the upper die assembly in a coining stroke until said stop bars engage against said frame.

6. In a coining die apparatus for shaping a housing section metal plate, a lower die assembly including a member having a plate supporting surface and a frame structure about said member projecting thereabove and defining therewith a plate receiving cavity, an upper die assembly and means for reciprocably driving said upper die assembly in coining strokes toward said lower die assembly and away from said lower die assembly, said upper die assembly including supporting means and stop bar structure projecting downwardly therefrom and engageable at the terminus of a coining stroke with said frame structure to define the limit of approach of the upper die assembly to said lower die assembly, said stop bar structure including plate retaining and shaping surface portions arranged to overhang a limited marginal area of said plate supporting member and thereby act upon a marginal area of a plate supported by said supporting member, coining punches carried by said upper die assembly within the confines of said stop bar structure, and means carried by said upper die assembly and operative for selectively activating said coining punches to operate coactively with said plate supporting member to coin selected areas of a plate supported by said supporting member, certain of said punches being contiguous to and cooperative with said overhanging surface portions of said stop bars for shaping marginal portions of the plate supported by said plate supporting member.

7. In a coining die apparatus for shaping a housing section metal plate, a lower die assembly including a member having a plate supporting surface and a frame structure about said member projecting thereabove and defining therewith a plate receiving cavity, an upper die assembly and means for reciprocably driving said upper die assembly in coining strokes toward said lower die assembly and away from said lower die assembly, said upper die assembly including supporting means and stop bar structure projecting downwardly therefrom and engageable at the terminus of a coining stroke with said frame structure to define the limit of approach of the upper die assembly to said lower die assembly, said stop bar structure including plate retaining and shaping surface portions arranged to overhang a limited marginal area of said plate supporting member and thereby act upon a marginal area of a plate supported by said supporting member, coining punches carried by said upper die assembly within the confines of said stop bar structure, means carried by said upper die assembly and operative for selectively activating said coining punches to operate coactively with said plate supporting member to coin selected areas of a plate supported by said supporting member, certain of said punches being contiguous to and cooperative with said overhanging surface portions of said stop bars for shaping marginal portions of the plate supported by said plate supporting member, and means for raising said plate supporting member relative to said frame structure for plate loading and unloading purposes.

8. In a coining die apparatus for shaping a housing section metal plate, a lower die assembly including a member having a plate supporting surface and a frame structure about said member projecting thereabove and defining therewith a plate receiving cavity, an upper die assembly and means for reciprocably driving said upper die assembly in coining strokes toward said lower die assembly and away from said lower die assembly, said upper die assembly including supporting means and stop bar structure projecting downwardly therefrom and engageable at the terminus of a coining stroke with said frame structure to define the limit of approach of the upper die assembly to said lower die assembly, said stop bar structure including plate retaining and shaping surface portions arranged to overhang a limited marginal area of said plate supporting member and thereby act upon a marginal area of a plate supported by said supporting member, coining punches carried by said upper die as- 10 sembly within the confines of said stop bar structure, means carried by said upper die assembly and operative for selectively activating said coining punches to operate coactively with said plate supporting member to coin selected areas of a plate supported by said supporting member, certain of said punches being continguous to and cooperative with said overhanging surface portions of said stop bars for shaping marginal portions of the plate supported by said plate supporting member, and means for raising said plate supporting member relative to said frame structure for plate loading and unloading purposes, said plate retaining and shaping surface portions of the stop bar structure carrying a series of pins projecting therefrom toward and supporting member to act upon said marginal area of a supported plate to form holes in said marginal area.

9. In a method of making a metal casing section, shaping a metal plate into polygonal outline of substantial size and predetermined thin cross-section and forming a marginal upstanding reinforcing rib on one face of the plate to be continuous about the entire outline of the plate to enable handling of the plate without undue danger of warpage or marginal deformation or damage, placing the preformed plate upon a conforming backing surface of a die assembly, coining the area of the plate within said rib into a pattern of depressions and crossing and connected reinforcing ribs and joining the ends of such crossing reinforcing ribs to said marginal rib, and during such coining shaping said marginal rib. 10. In a method of shaping a housing casing section to be joined with other sections in fabrication of a housing, preforming a polygonal metal plate of predetermined thickness to a predetermined plane and with a partially raised reinforcing rib entirely thereabout on the margin of one face, progressively coining limited adjacent areas of said one face and thereby displacing material from said areas until a substantially thinner cross-section is attained than said predetermined thickness, in such displacement shaping the displaced material into raised reinforcing ribs bounding and separating said areas, and continuing said coining until the entire area inside said preformed rib has been coined. 11. In a method for shaping a housing blank to provide a thin membrane wall with integral reinforcing ribs,

supporting one face of a metal blank of greater thickness than the desired membrane thickness, effecting coining pressure toward the supported metal blank by succesively subjecting the blank to coining pressure of independently and successively ope-rable coining punches and thereby coining predetermined limited areas of the blank successively into a pattern of substantially thinner areas than the predetermined thickness until the blank has been coined over an entire predetermined area thereof, and maintaining the punches separated to a predetermined extent to afford rib-receiving spaces therebetween and displacing material of the blank into such spaces to form raised ribs during application of coining pressure by the punches. 12. In apparatus for shaping a housing casing section to be joined with other sections in fabrication of a housing,

means for supporting a preformed metal plate of predetermined thickness and plane and having a partially raised rib entirely thereabout on the margin of one face, means for progresively coining limited adjacent areas of said one face and thereby displacing material from said areas until a substantially thinner crosssec-tion is attained than said predetermined thickness, means for shaping the displaced material into raised reinforcing ribs bounding and separating said areas,

11 said means being operable continuously and progressively until the entire area inside said preformed raised rib has been coined, and means :oornprising a shaping groove and sizing punch rib structure operative during said displacement of material to accommodate increase in height of said preformed rib and size the same.

13. Apparatus as defined in claim 12, including a spaced series of pins mounted rigidly in said groove adjacent to said sizing rib structure and operative to form corresponding series of indexing holes in the raised portion of the marginal preformed rib.

References Cited by the Examiner UNITED STATES PATENTS Watson 2953'1 Speller 29-1935 X De Salardi 2934 Sherman 29552 X Reed 29-552 Duhame-l 29534 10 CHARLES W. LANHAM, Primary Examiner.

I. C. HOLMAN, Assistant Examiner. 

4. IN APPARATUS FOR SHAPING METAL PLATE HOUSING SECTIONS, A SUPPORTING DIE ASSEMBLY HAVING A MEMBER FOR SUPPORTING AND FIRMLY BACKING A METAL SECTION BLANK OF PREDETERMINED THICKNESS, A COINING DIE ASSEMBLY COMPRISING A SUPPORTING MEMBER CARRYING A GRID ARRANGEMENT OF VERTICAL STRIP BARS DEFINING VERTICAL PUNCH SOCKETS, COINING PUNCHES SUPPORTED IN SAID SOCKETS AND DIVIDED BY SAID STRIP BARS, GAG MEMBER COOPERABLE BETWEEN SAID SUPPORTING MEMBER AND SAID PUCHES TO LOCK SAID PUNCHES SELECTIVELY IN COINING POSITIONS WHILE LEAVING OTHER OF THE PUNCHES IN NON-COINING RELATION, AND MEANS FOR DRIVING THE SUPPORTING MEMBER AND SAID GAG PUNCHES INTO COINING RELATION TO THE BLANK SUPPORTED BY THE SUPPORTING MEMBER. 